Question

我有GeoJSON文件。但问题是，我不知道这个文件的投影。现在，我想覆盖我的基本地图（OSM）。我该怎么办？此GeoJSON文件包含斯德哥尔摩地区的功能。我该如何为此设置边界框？我尝试了几个来自托管网站的openlayers示例。但是，这些对我不起作用。我从（http://dev.openlayers.org/releases/OpenLayers-2.11/examples/all-overlays.html）得到了一个与我想要的非常相似的例子。我检查了他使用边界框的源代码。但问题是，如果我删除边界框这个例子不起作用（我用这个给定数据绑定）。我不知道，我的json文件有什么问题吗？贝娄，我已经提供了一些样本数据。格式好吗？正如我所说，我尝试过不同的方式。有时我从脚本中读取json文件。但是，它无法显示精选叠加ed地图。贝娄，我给出了示例代码，显示了我的尝试方式。

{
"type": "FeatureCollection",
"features": [
{ "type": "Feature", "properties": { "FNODE_": 387603, "TNODE_": 387603, "LPOLY_": 0, "RPOLY_": 0, "LENGTH": 89.206900, "ROADS_SWER": 519006, "ROADS_SW_1": 519006, "REF": "", "TYPE": "residential", "ONEWAY": 8224, "BRIDGE": 8224, "MAXSPEED": 0, "LENGTH_M": 89.500000, "ID": 0, "dist_fnode": 13655.200000, "dist_tnode": 13655.200000 }, "geometry": { "type": "LineString", "coordinates": [ [ 676868.875000, 6569872.000000 ], [ 676882.437500, 6569861.000000 ], [ 676894.062500, 6569851.500000 ], [ 676894.500000, 6569844.500000 ], [ 676891.812500, 6569840.500000 ], [ 676887.312500, 6569841.000000 ], [ 676882.187500, 6569843.000000 ], [ 676875.250000, 6569850.000000 ], [ 676868.125000, 6569858.500000 ], [ 676866.500000, 6569867.000000 ], [ 676868.875000, 6569872.000000 ] ] } }
,

{ "type": "Feature", "properties": { "FNODE_": 387723, "TNODE_": 387724, "LPOLY_": 0, "RPOLY_": 0, "LENGTH": 9.581310, "ROADS_SWER": 519163, "ROADS_SW_1": 519163, "REF": "", "TYPE": "service", "ONEWAY": 8224, "BRIDGE": 8224, "MAXSPEED": 0, "LENGTH_M": 9.500000, "ID": 1, "dist_fnode": 13705.100000, "dist_tnode": 13695.600000 }, "geometry": { "type": "LineString", "coordinates": [ [ 677125.375000, 6569906.500000 ], [ 677133.437500, 6569911.500000 ] ] } }
, 
..
..
]
}

代码示例----

//OSM Layer-----------------------------------------------
var layer = new OpenLayers.Layer.OSM( "Simple OSM Map");

//GeoJSON Layer-------------------------------------------
var vector_format = new OpenLayers.Format.GeoJSON({}); 
var vector_protocol = new OpenLayers.Protocol.HTTP({
    url: 'ml/roads.json',
    format: vector_format
});
var vector_strategies = [new OpenLayers.Strategy.Fixed()];
var vector_layer = new OpenLayers.Layer.Vector('More Advanced Vector Layer',{
    protocol: vector_protocol,
    strategies: vector_strategies,
    isBaseLayer: false
});

var options = {
    layers: [layer, vector_layer]
};
var map = new OpenLayers.Map("map", options);
//Projection-----------------------------------------------
map.setCenter(
    new OpenLayers.LonLat(18.068611, 59.329444).transform(
        new OpenLayers.Projection("EPSG:4326"),
            map.getProjectionObject()
    ), 10
);

提前谢谢。

Answer 1

vector_layer.events.on({
    loadend: function() {
        map.zoomToExtent(vector_layer.getDataExtent());
    }
});

我仍然认为你应该在地图构造函数中设置你的投影......

如何从GeoJSON文件中获取Bounding box值？

1 个答案: